Current evidence for the organic etiology of spastic dysphonia.

For over 100 years it has been universally assumed in the literature that spastic dysphonia is a functional or psychoneurotic voice disorder. In the last few years, new data have accumulated that support the concept that spastic dysphonia is caused by an organic, rather than a functional, abnormality. Histologic examination of segments of the recurrent laryngeal nerve removed from patients with spastic dysphonia has revealed myelin abnormalities in 30% of the nerves examined. Neurologic examination indicated brain stem or basal ganglia disturbances in some patients who had no apparent nerve disease.